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Abstract:

Organometallic compounds and organic electroluminescence devices
employing the same are provided. The organometallic compound has a
chemical structure represented below:
##STR00001## wherein, X is C--H or N, Y is CH2 or NH; R1 is
H, or C1-8 alkyl; and A1 is acetylacetone ligand, acetylacetone
with phenyl group ligand, or derivatives thereof.

Claims:

1. An organometallic compound having a Formula (I) or Formula (II), of:
##STR00025## wherein, X is C--H or N, Y is CH2 or NH; R1 is H,
or C1-8 alkyl; and A1 is acetylacetone ligand, acetylacetone
with phenyl group ligand, or derivatives thereof.

2. The organometallic compound as claimed in claim 1, wherein A1 is
bonded with Ir via an oxygen atom on one side, and bonded with Ir via
another oxygen atom on the other side.

6. An organic electroluminescence device, comprising: a pair of
electrodes; and an electroluminescent element disposed between the pair
of electrodes, wherein the electroluminescent element comprises the
organometallic compound as claimed in claim 1.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is based upon and claims the benefit of priority
from the prior Taiwan Patent Application No. 100127917, filed on Aug. 5,
2011, the entire contents of which are incorporated herein by reference.

BACKGROUND

[0002] 1. Field

[0003] The disclosure relates to an organometallic compound and organic
electroluminescence device employing the same and, more particularly, to
a phosphorescent organometallic compound and a phosphorescent organic
electroluminescence device employing the same.

[0004] 2. Description

[0005] Recently, with the development and wide application of electronic
products, such as mobile phones, PDAs, and notebook computers, there has
been increasing demand for flat display elements which consume less
electric power and occupy less space. Organic electroluminescent devices
are self-emitting and highly luminous, with wide viewing angles, fast
response speeds, and simple fabrication methods, making them an industry
display of choice.

[0006] Generally, an organic electroluminescent device is composed of a
light-emission layer sandwiched between a pair of electrodes. When an
electric field is applied to the electrodes, the cathode injects
electrons into the light-emission layer and the anode injects holes into
the light-emission layer. When the electrons recombine with the holes in
the light-emission layer, excitons are formed. Recombination of the
electron and hole results in light emission.

[0007] Depending on the spin states of the hole and electron, the exciton,
which results from the recombination of the hole and electron, can have
either a triplet or singlet spin state. Luminescence from a singlet
exciton results in fluorescence whereas luminescence from a triplet
exciton results in phosphorescence. The emissive efficiency of
phosphorescence is three times that of fluorescence. Therefore, it is
crucial to develop highly efficient phosphorescent material, in order to
increase the emissive efficiency of an OLED.

[0008] Conventional red phosphorescent materials, however, exhibit lower
electroluminescent efficiency, thereby it is difficult to fabricate a
high CRI white electroluminescent device by employing conventional red
phosphorescent materials. Further, a red light emitted by an OLED is
useful for wound healing and thus it the can be utilized for the
development of therapeutics for wounds.

[0009] Therefore, it is necessary to develop novel organic compounds
suitable for red phosphorescent OLEDs to solve the above problems.

BRIEF SUMMARY

[0010] An exemplary embodiment of an organometallic compound has a Formula
(I) or Formula (II), of:

##STR00002##

[0011] wherein, X is C--H or N, Y is CH--, or NH; R1 is H, or
C1-8 alkyl; and A1 is acetylacetone ligand, acetylacetone with
phenyl group ligand, or derivatives thereof.

[0012] In another exemplary embodiment of the disclosure, an organic
electroluminescent device is provided. The device includes a pair of
electrodes and an electroluminescent element disposed between the pair of
electrodes, wherein the electroluminescent element includes the
aforementioned organometallic compound (serving as a red dopant).

[0013] A detailed description is given in the following embodiments with
reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The disclosure can be more fully understood by reading the
subsequent detailed description and examples with references made to the
accompanying drawings, wherein:

[0015] FIG. 1 shows a cross section of an organic electroluminescent
device disclosed by an embodiment of the disclosure.

DETAILED DESCRIPTION

[0016] The following description is of the best-contemplated mode of
carrying out the disclosure. This description is made for the purpose of
illustrating the general principles of the disclosure and should not be
taken in a limiting sense. The scope of the disclosure is best determined
by reference to the appended claims.

[0017] The disclosure provides an organometallic compound prepared by
introducing a 4-phenylnaphtho[1,2-b]thiophene moiety, wherein an obtained
organometallic compound is suitable for use in an electroluminescence
device for emitting red light. Moreover, the organometallic compound of
the disclosure can be applied in an organic electroluminescent device for
enhancing the electroluminescent efficiency thereof.

[0018] Organometallic Compound

[0019] The disclosure provides an organometallic compound having a
structure represented by Formula (I) or Formula (II):

[0021] According to an embodiment of the disclosure, A1 is bonded
with Ir via an oxygen atom on one side, and bonded with Ir via another
oxygen atom on the other side.

[0022] According to some embodiments of the disclosure, the organometallic
compound of the disclosure can have a structure represented by Formula
(III), Formula (IV) or Formula (V), of:

##STR00004##

[0023] wherein, R1 is hydrogen, or C1-8 alkyl group; R2 is
hydrogen, phenyl, or biphenyl; and Y is CH2, or NH.

[0024] The organometallic compounds according to Formula (I) and Formula
(II) of the disclosure include the following compounds shown in Table 1.
In addition, the contraction thereof are also named and shown in Table 1.

[0025] In order to clearly illustrate the method for preparing
organometallic compounds according to Formula (I) and Formula (II), the
preparation of compounds disclosed in Examples 1-4 are described in
detail as below.

Example 1

Preparation of Compound Ir-THQ-acac

[0026] First, compound (1) (2-(2-aminoethyl)thiophene, 2.0 g, 10.0 mmol)
and 50 mL toluene were added into a 250 mL bottle. Next, compound (2)
(1.29 g, 10.00 mmole), K2CO3 (2M, 20 mL), Pd(PPH3)4
(0.43 g), and (t-Bu)3P (0.23 g) were added into the bottle at room
temperature. After heating to reflux, the NaOH aqueous solution (20%) was
added into the bottle and stirred overnight. After purification, compound
(3) with a yield of 69% was obtained. The synthesis pathway was as
follows:

##STR00009##

[0027] Next, compound (3) (1.0 g, 4.90 mmol), Iron powder, a mixed solvent
(EtOH:AcOH:H2O=2:2:1, 50 mL) were added into a 250 mL bottle. After
heating to reflux for 15 min, the mixture was stirred at room temperature
for 25 min. After filtration to remove the Iron powder, the result was
neutralized by NaHCO3 and then extracted by ethyl acetate and water.
After concentration, compound (4) with a yield of 91% was obtained. The
synthesis pathway was as follows:

##STR00010##

[0028] Next, compound (4) (1.00 g, 5.70 mmole) and toluene (100 mL) were
added into a 250 mL bottle. After heating to reflux, trifluoroacetic acid
(1 eq) and compound (5) (0.97 g) were added into the bottle. Next, the
mixture was heated to reflux under an oxygen atmosphere. After reaction,
compound (6) with a yield of 79% was obtained. The synthesis pathway was
as follows:

K2CO3 (0.76 g), and 30 mL 2-methoxyethanol were added into the
bottle. After reacting for 24 hrs, the bottle was cooled down to room
temperature and the reaction was quenched by adding water (50 mL). The
result was purified by column chromatography with
n-hexane/dichloromethane (3:1), obtaining Ir-THQ-acac. The synthesis
pathway was as follows:

##STR00013##

[0030] The physical measurement of the compound Ir-THQ-acac is listed
below:

[0032] First, compound (6) (3.68 g, 11.60 mmol), IrCl3.xH2O
(1.65 g), 2-methoxy ethanol (15 mL), and water (5 mL) were added into a
100 mL bottle. After heating to 140° C. for 24 hrs, compound
(7)(1.30 g), K2CO3 (0.76 g), and 30 mL 2-methoxyethanol were
added into the bottle. After reacting for 24 hrs, the bottle was cooled
down to room temperature and the reaction was quenched by adding water
(50 mL). The result was purified by column chromatography with
n-hexane/dichloromethane (3:1), obtaining Ir-THQ-phac. The synthesis
pathway was as follows:

##STR00014##

[0033] The physical measurement of the compound Ir-THQ-phac is listed
below:

[0036] Next, compound (10) (1.0 g, 4.90 mmol), lion powder (2.17 g, 38.90
mmol), a mixed solvent (EtOH:AcOH:H2O=2:2:1, 50 mL) were added into
a 250 mL bottle. After heating to reflux for 15 min, the mixture was
stirred at room temperature for 25 min. After filtration to remove the
Iron powder, the result was neutralized by NaHCO3 and then extracted by
ethyl acetate and water. After concentration, compound (11) was obtained.
The synthesis pathway was as follows:

##STR00016##

[0037] Next, compound (11) (1.00 g, 5.70 mmole) and toluene (100 mL) were
added into a 250 mL bottle. After heating to retlux, trifluoroacetic acid
(1 eq) and compound (5) (0.97 g) were added into the bottle. Next, the
mixture was heated to reflux under an oxygen atmosphere. After reaction,
compound (12) with a yield of 72% was obtained. The synthesis pathway was
as follows:

K2CO3 (0.76 g), and 30 mL 2-methoxyethanol were added into the
bottle. After reacting for 24 hrs, the bottle was cooled down to room
temperature and the reaction was quenched by adding water (50 mL). The
result was purified by column chromatography with
n-hexane/dichloromethane (3:1), obtaining Ir-THQ-N-acac. The synthesis
pathway was as follows:

##STR00019##

Example 4

Preparation of Compound Ir-THQ-N-phac

[0039] Compound (12) (3.68 g, 11.60 mmol), IrCl3.xH2O (1.65 g),
2-methoxy ethanol (15 mL), and water (5 mL) were added into a 100 mL
bottle. After heating to 140° C. for 24 hrs, compound (7) (1.30
g), K2CO3 (0.76 g), and 30 mL 2-methoxyethanol were added into
the bottle. After reacting for 24 hrs, the bottle was cooled down to room
temperature and the reaction was quenched by adding water (50 mL). The
result was purified by column chromatography with
n-hexane/dichloromethane (3:1), obtaining Ir-THQ-N-phac. The synthesis
pathway was as follows:

##STR00020##

[0040] Organic Electroluminescent Device

[0041] FIG. 1 shows an embodiment of an organic electroluminescent device
10. The electroluminescent device 100 includes a substrate 12, a bottom
electrode 14, an electroluminescent element 16, and a top electrode 18,
as shown in FIG. 1. The organic electroluminescent device can be
top-emission, bottom-emission, or dual-emission devices.

[0042] The substrate 12 can be a glass plastic, or semiconductor
substrate. Suitable materials for the bottom and top electrodes can be
Ca, Ag, Mg, Al, Li, In, Au, Ni, W, Pt, Cu, indium tin oxide (ITO), indium
zinc oxide (IZO), aluminum zinc oxide (AZO), or zinc oxide (ZnO), formed
by sputtering, electron beam evaporation, thermal evaporation, or
chemical vapor deposition. Further, at least one of the bottom and top
electrodes 14 and 18 is transparent.

[0043] The electroluminescent element 16 at least includes an emission
layer, and can further include a hole injection layer, a hole transport
layer, an electron transport layer, and an electron injection layer. In
an embodiment of the disclosure, at least one layer of the
electroluminescent element 16 includes the aforementioned organometallic
compound.

[0044] According to an embodiment of the disclosure, the organic
electroluminescent device can be a phosphorescent organic
electroluminescent device, and the phosphorescent organic
electroluminescent device can include an emission layer including a host
material and a phosphorescent dopant, wherein the host material includes
the aforementioned organometallic compounds.

[0045] In order to clearly disclose the organic electroluminescent devices
of the disclosure, the following examples (employing the organometallic
compounds of Example 1 serving as dopant) are intended to illustrate the
disclosure more fully without limiting their scope, since numerous
modifications and variations will be apparent to those skilled in this
art.

Example 5

[0046] A glass substrate with an indium tin oxide (ITO) film of 100 nm was
provided and then washed with a cleaning agent, acetone, and isopropanol
with ultrasonic agitation. After drying with a nitrogen flow, the ITO
film was subjected to a UV/ozone treatment. Next,
NPB(N,N'-di(naphthalene-1-yl)-N,N'-diphenyl-benzidine, with a thickness
of 40 nm), CBP(4,4'-N,N'-dicarbazole-biphenyl) doped with Ir-THQ-acac

##STR00021##

(the ratio between CBP and Ir-THQ-acac was 100:3, with a thickness of 30
nm), Bphen (4,7-diphenyl-1,10-phenanthroline, with a thickness of 30 nm),
LiF (with a thickness of 0.5 nm), and Al (with a thickness of 120 nm)
were subsequently formed on the ITO film at 10-6 Pa, obtaining the
electroluminescent device (1). The materials and layers formed therefrom
are described in the following:

[0048] The optical property of the electroluminescent device (1), as
described in Example 5, was measured by a PR650 (purchased from Photo
Research Inc.) and a Minolta TS110. The results are shown below:

[0049] Optimal efficiency: 34.1 cd/A, 19.5 lm/W;

[0050] Emissive efficiency: 11.9 cd/A, 4.2 lm/W@1000 cd/m2;

[0051] Electroluminescent wavelength: 612 nm;

[0052] CIE coordinations: (0.63, 0.35).

Example 6

[0053] A glass substrate with an indium tin oxide (ITO) film of 100 nm was
provided and then washed with a cleaning agent, acetone, and isopropanol
with ultrasonic agitation. After drying with a nitrogen flow, the ITO
film was subjected to a UV/ozone treatment. Next,
NPB(N,N'-di(naphthalene-1-yl)-N,N'-diphenyl-benzidine, with a thickness
of 40 nm), CBP(4,4'-N,N'-dicarbazole-biphenyl) doped with Ir-THQ-acac

##STR00022##

(the ratio between CBP and Ir-THQ-acac was 100:4, with a thickness of 30
nm), Bphen (4,7-diphenyl-1,10-phenanthroline, with a thickness of 30 nm),
LiF (with a thickness of 0.5 nm), and Al (with a thickness of 120 nm)
were subsequently formed on the ITO film at 10-6 Pa, obtaining the
electroluminescent device (2). The materials and layers formed therefrom
are described in the following:

[0055] The optical property of the electroluminescent device (2), as
described in Example 6, was measured by a PR650 (purchased from Photo
Research Inc.) and a Minolta TS110. The results are shown below:

[0056] Optimal efficiency: 35.9 cd/A, 28.21 m/W;

[0057] Emissive efficiency: 11.4 cd/A, 5.71 m/W @1000 cd/m2;

[0058] Electroluminescent wavelength: 616 nm;

[0059] CIE coordinations: (0.65, 0.34).

Example 7

[0060] A glass substrate with an indium tin oxide (ITO) film of 100 nm was
provided and then washed with a cleaning agent, acetone, and isopropanol
with ultrasonic agitation. After drying with a nitrogen flow, the ITO
film was subjected to a UV/ozone treatment. Next,
NPB(N,N'-di(naphthalene-1-yl)-N,N'-diphenyl-benzidine, with a thickness
of 40 nm), CBP(4,4'-N,N'-dicarbazole-biphenyl) doped with Ir-THQ-acac

##STR00023##

(the ratio between CBP and Ir-THQ-acac was 100:5, with a thickness of 30
nm), Bphen (4,7-diphenyl-1,10-phenanthroline, with a thickness of 30 nm),
LiF (with a thickness of 0.5 nm), and Al (with a thickness of 120 nm)
were subsequently formed on the ITO film at 10-6 Pa, obtaining the
electroluminescent device (3). The materials and layers formed therefrom
are described in the following: NPB(40 nm)/CBP: Ir-THQ-acac (4%)(30
nm)/Bphen (30 nm)/LiF(0.5 nm)/Al(120 nm)

[0061] The optical property of the electroluminescent device (3), as
described in Example 7, was measured by a PR650 (purchased from Photo
Research Inc.) and a Minolta TS110. The results are shown below:

[0062] Optimal efficiency: 18.7 cd/A, 9.7 lm/W;

[0063] Emissive efficiency: 10.0 cd/A, 3.5 lm/W @1000 cd/m2;

[0064] Electroluminescent wavelength: 616 nm;

[0065] CIE coordinations: (0.65, 0.34).

[0066] While the disclosure has been described by way of example and in
terms of the preferred embodiments, it is to be understood that the
disclosure is not limited to the disclosed embodiments. To the contrary,
it is intended to cover various modifications and similar arrangements
(as would be apparent to those skilled in the art). Therefore, the scope
of the appended claims should be accorded the broadest interpretation so
as to encompass all such modifications and similar arrangements.

Example 8

[0067] A glass substrate with an indium tin oxide (ITO) film of 100 nm was
provided and then washed with a cleaning agent, acetone, and isopropanol
with ultrasonic agitation. After drying with a nitrogen flow, the ITO
film was subjected to a UV/ozone treatment. Next,
NPB(N,N'-di(naphthalene-1-yl)-N,N'-diphenyl-benzidine, with a thickness
of 40 nm), CBP(4,4'-N,N'-dicarbazole-biphenyl) doped with Ir-THQ-acac

##STR00024##

(the ratio between CBP and Ir-THQ-acac was 100:4, with a thickness of 30
nm), Bphen (4,7-diphenyl-1,10-phenanthroline, with a thickness of 30 nm),
LiF (with a thickness of 0.5 nm), and Al (with a thickness of 120 nm)
were subsequently formed on the ITO film at 10-6 Pa, obtaining the
electroluminescent device (4). The materials and layers formed therefrom
are described in the following: NPB(40 nm)/BAlq: Ir-THQ-acac (4%)(30
nm)/Bphen (30 nm)/LiF(0.5 nm)/Al(120 nm)

[0068] The optical property of the electroluminescent device (4), as
described in Example 8, was measured by a PR650 (purchased from Photo
Research Inc.) and a Minolta TS110. The results are shown below:

[0069] Optimal efficiency: 14.2 cd/A, 7.4 lm/W;

[0070] Emissive efficiency: 11.5 cd/A, 4.8 μm/W @1000 cd/m2;

[0071] Electroluminescent wavelength: 620 nm;

[0072] CIE coordinations: (0.65, 0.35).

[0073] While the disclosure has been described by way of example and in
terms of the preferred embodiments, it is to be understood that the
disclosure is not limited to the disclosed embodiments. To the contrary,
it is intended to cover various modifications and similar arrangements
(as would be apparent to those skilled in the art). Therefore, the scope
of the appended claims should be accorded the broadest interpretation so
as to encompass all such modifications and similar arrangements.